This invention relates to check valves, and more particularly to a center flow check valve for use in an I.V. administration set.
Check valves for a variety of different applications are well known. The purpose of a check valve is to allow fluid to flow in only one direction. In the medical field, it is advantageous to include one or more check valves in the tubing set used during interveinous infusion of fluids to a patient. Such fluids often include drugs. It is therefore desirable to limit the size of the check valve in order to minimize the volume of fluid containing the drugs which fills the valve and is generally thrown away with the valve.
Samples of various check valve designs are depicted in U.S. Pat. Nos. 4,415,003, 4,369,812 and 4,286,628 to Paradis et al., U.S. Pat. Nos. 4,535,820, 4,310,017 and 4,246,932 to Raines, U.S. Pat. No. 4,222,407 to Ruschke et al., and U.S. Pat. No. 3,889,710 to Brost. As disclosed in many of these patents, it is very common in check valves to use a flexible diaphragm (often called a disk) to seal off a flow path through the valve body to prevent back flow. One problem often encountered in using a disk in a check valve is a difficulty in keeping the disk properly positioned in relation to the flow path and the sealing surface against which it is to act. One solution to this problem has been to provide a hole in the disk through which a mounting pin extends, holding the disk against transverse movement. In a known design of this type, however, the flow pattern through the valve cannot be centered around the disk since the mounting pin extends from the central portion of a valve body.
Other problems often encountered in check valves using flexible disks is that the disk is held in a position which overly stresses the disk member, causing valve sticking and leading to early failure of the disk member.
When used in disposable I.V. administration sets, the cost of the valve is very important, since it is generally disposed of after a single use.